The intertidal zone is the area between the high tide and low tide marks, where the land and ocean meet. It is a dynamic and diverse ecosystem that experiences fluctuating water levels and salinity.

Coastal ecosystems are generally highly productive due to the abundance of nutrients and sunlight. They support a wide variety of marine life and play a crucial role in the global carbon cycle.

The continental shelf typically extends to a depth of around 200 meters, where it meets the continental slope.

Coastal and marine ecosystems face multiple threats, including climate change, overfishing, pollution, habitat destruction, and invasive species. These threats can have devastating impacts on biodiversity, ecosystem functioning, and the livelihoods of coastal communities.

Upwelling is the process by which nutrient-rich deep ocean water rises to the surface, bringing essential nutrients to the photic zone and supporting high levels of primary productivity.

Sea otters are considered keystone species in coastal ecosystems because they play a crucial role in maintaining the balance of the ecosystem. By preying on sea urchins, they prevent overgrazing of kelp forests, which are important habitats for a variety of marine life.

Accretion is the process by which salt marshes and mangrove forests trap and accumulate sediments, helping to build and stabilize coastlines. This process is important for protecting coastal communities from erosion and storm surges.

Coral reefs are not considered coastal wetlands. They are underwater ecosystems formed by colonies of coral polyps and are found in tropical and subtropical waters.

Bathymetry refers to the vertical zonation of marine organisms based on their depth range. It divides the ocean into different depth zones, such as the intertidal zone, the continental shelf, the abyssal plain, and the hadal zone.

Increased water temperature is a major cause of coral bleaching, which occurs when corals expel the symbiotic algae that provide them with nutrients and color. This can lead to the loss of coral reefs, which are important ecosystems for biodiversity and fisheries.

Calcification is the process by which marine organisms produce and release calcium carbonate shells or skeletons, contributing to the formation of marine sediments. This process is important for the cycling of carbon and the formation of geological structures such as coral reefs.

The Great Barrier Reef Marine Park is a marine protected area established to conserve the biodiversity and ecosystems of the Great Barrier Reef, the world's largest coral reef system.

Ocean currents are the movement of water in the ocean caused by differences in density, wind, and the rotation of the Earth. They play a crucial role in distributing heat, nutrients, and oxygen throughout the ocean.

Diatoms, dinoflagellates, and coccolithophores are all major types of phytoplankton, microscopic algae that form the base of the marine food web. They are responsible for a significant portion of the Earth's primary productivity and play a crucial role in the cycling of carbon and oxygen.

Adaptation is the process by which marine organisms adapt to changes in their environment over time. This can involve changes in their physical characteristics, behavior, or physiology to better suit their changing environment.